System and Method for All Electrical Operation of a Mining Haul Truck

ABSTRACT

A mining haul truck driven by electrical wheel motors is operated with all electrical power sources; that is, without a diesel engine. While travelling on the loading site, the mining haul truck is powered by an on-board energy storage system, which may include a bank of ultracapacitors. The mining haul truck then moves to the bottom of a trolley ramp and is coupled to trolley lines. While travelling uphill, the mining haul truck is powered by the trolley lines, and the on-board energy storage system is charged by the trolley lines. When the mining haul truck reaches the top of the trolley ramp, the mining haul truck is uncoupled from the trolley lines. While travelling on the unloading site, the mining haul truck is powered by the on-board energy storage system. The on-board energy storage system may also be charged by retard energy generated by the wheel motors during braking.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/038,995 filed 27 Sep. 2013 in the US Patent and TrademarkOffice, the content of which is hereby incorporated herein in itsentirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to power systems for mining haultrucks, and more particularly to a system and method for all electricaloperation of a mining haul truck.

Mining haul trucks are typically equipped with electrical drive motors.Under demanding conditions, such as travel on an uphill grade,electrical power can be supplied by a trolley line. The mining haultruck draws electrical power from the trolley line via a pantograph.Under some travel conditions, such as inside a mining pit, around acrusher, and on level surfaces, however, the mining haul truck operatesindependently of a trolley line. Electrical power is then supplied by anelectrical generator powered by a diesel engine. Diesel engines requiredelivery and storage of a supply of fuel and require regularmaintenance. The exhaust gases from diesel engines, furthermore,contribute to air pollution.

BRIEF SUMMARY OF THE INVENTION

In an embodiment of the invention, a mining haul truck driven byelectrical motors is operated from all electrical power sources, withoutthe need for a diesel engine driving a generator. When the mining haultruck is travelling on substantially flat ground, electrical power issupplied by an on-board energy storage system. When the mining haultruck is travelling along an uphill grade, electrical power is suppliedby trolley lines. The on-board energy storage system is also chargedwith electrical power from the trolley lines. In an embodiment of theinvention, the on-board energy storage system is charged with retardenergy captured from the electrical motors during braking.

These and other advantages of the invention will be apparent to those ofordinary skill in the art by reference to the following detaileddescription and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a single-line diagram of a prior-art diesel-poweredelectrical system for a mining haul truck;

FIG. 2 shows a single-line diagram of a prior-art trolley power systemfor a mining haul truck;

FIG. 3 shows a schematic of a first travel scenario for a mining haultruck;

FIG. 4 shows a schematic of a second travel scenario for a mining haultruck;

FIG. 5A and FIG. 5B show a flowchart of a process for all electricaloperation of a mining haul truck;

FIG. 6 shows a schematic of a power system with an ultracapacitor energystorage system;

FIG. 7 shows a plot of vehicle speed as a function of travel time and aplot of vehicle acceleration as a function of travel time;

FIG. 8 shows a plot of vehicle tractive effort as a function of traveltime and a plot of vehicle drive drag as a function of travel time;

FIG. 9 shows a plot of travel distance as a function of travel time; and

FIG. 10 shows a schematic of an ultracapacitor energy managementcontroller.

DETAILED DESCRIPTION

FIG. 1 shows a single-line diagram of a prior-art mining haul truckpower system. The mining haul truck has two drive wheels. Each wheel isdriven by a 3-phase alternating-current (AC) wheel motor (M). The wheelmotors are referenced as the wheel motor 110 and the wheel motor 114.Electrical power is supplied by a diesel engine 102 driving a 3-phase ACgenerator (G) 104. (Other types of mechanical engines may be used;diesel engines are typical in mining operations.) The coupling 124couples the diesel engine 102 to the generator 104. The diesel engine102 and the generator 104 are mounted on the mining haul truck. The ACoutput of the generator 104 is fed into the rectifiers 106. The directcurrent (DC) output of the rectifiers 106 is fed into a set ofinverters. The inverters 108 supply 3-phase AC power to the wheel motor110. Similarly, the inverters 112 supply 3-phase AC power to the wheelmotor 114. The chopper 116 and the power resistor grid 118 dissipateenergy from the wheel motor 110 during braking action. Similarly, thechopper 120 and the power resistor grid 122 dissipate energy from thewheel motor 114 during braking action. Braking action is described inmore detail below.

In the power system shown in FIG. 1, the entire power requirements forthe wheel motor 110 and the wheel motor 114 are supplied by the dieselengine 102. Performance (as determined, for example, by acceleration andspeed) of the mining haul truck is limited by the power capacity of thediesel engine. In particular, when the mining haul truck, filled with aheavy payload, is travelling along an uphill grade, the diesel enginemay be stressed to maximum capacity. One method for reducing the powerdemand on the diesel engine as the mining haul truck travels on anuphill grade is to power the wheel motors entirely via electrical powerdrawn from a trolley line. During this operational mode, the generator104 is disconnected from the diesel engine 102 via the coupling 124. Thediesel engine then idles on uphill grades. As a result, fuel consumptionis reduced by ˜95%; noise and exhaust emissions are reduced; andproductivity and engine life are increased.

FIG. 2 shows a single-line diagram of a prior-art mining haul truckpower system including an overhead trolley power system. Similar to thepower system shown in FIG. 1, the diesel engine 202 is connected via thecoupling 204 to the 3-phase AC generator 206. The AC output of thegenerator 206 is fed into the rectifiers 208. The DC output of therectifiers 208 is fed into the inverters 210, which provide power to thewheel motor 212, and into the inverters 218, which provide power to thewheel motor 220.

The inputs of the inverters 210 and the inverters 218 can also beconnected to DC power supplied by the electric substation 250 via thetrolley line 230 and the trolley line 232. A trolley line is alsoreferred to as an overhead line. Electrical connection of the mininghaul truck to the trolley line 230 and the trolley line 232 isimplemented via the pantograph arm 234 and the pantograph arm 236,respectively. The throw switch 240 connects/disconnects the inputs ofthe inverters 210 and the inverters 218 to the trolley line 230 and thetrolley line 232. There is also an auxiliary breaker 238. As mentionedabove, when the mining haul truck is powered by the trolley powersystem, the diesel engine 202 is typically disconnected from thegenerator 206 via the coupling 204.

FIG. 3 shows a mining site in which the loading site is downhill fromthe unloading site; for example, the loading site is at the bottom of apit, and the payload is trucked out of the pit. The loading site 309 islocated within the region 321. Within the region 321, the mining haultruck 302 is not powered by trolley lines. The unloading site 339 islocated within the region 351. Within the region 351, the mining haultruck 302 is not powered by trolley lines. Typically, the terrain withinthe region 321 and within the region 351 is substantially flat.

In the uphill direction, the region 321 and the region 351 are connectedby the trolley ramp 371, along which electrical power is available fromthe trolley lines 370 (for simplicity, the trolley lines 370 refer to apair of trolley lines). In the downhill direction, the region 351 andthe region 321 are connected by the trolley ramp 361, along whichelectrical power is available from the trolley lines 360. The trolleylines 370 and the trolley lines 360 are supported overhead by thesupport arms 312 mounted on the support poles 310.

In an embodiment of the invention, the mining haul truck is equippedwith an on-board energy storage system (OBESS) that provides electricalpower when the mining haul truck is operating within region 321 orwithin region 351. A diesel engine and generator are not needed. AnOBESS refers to an energy storage system that travels with the mininghaul truck (for example, mounted on the mining haul truck or attached tothe mining haul truck or mounted on a trailer attached to the mininghaul truck). In an embodiment of the invention, an OBESS includes a bankof ultracapacitors, a bank of batteries, or a bank of ultracapacitorsand a bank of batteries. Further details of an OBESS are provided below.All electrical operation of the mining haul truck is first described.

Refer to travel scenario shown in FIG. 3. Powered by the OBESS, themining haul truck 302 starts in region 321 at position P 301 and movesto the loading site 309. At the loading site 309, an electric shovel(not shown) fills the payload 304 (such as ore) onto the mining haultruck 302, which then leaves the loading site 309 at position P 303. Themining haul truck 302 then moves to position P 305, the entrance to thetrolley ramp 371. The mining haul truck 302 is coupled to the trolleylines 370. Under trolley power (trolley power refers to electrical powerdrawn from the trolley lines), the mining haul truck 302 moves up thetrolley ramp 371 (shown as position P 373) and arrives at position P331. While the mining haul truck 302 is coupled to the trolley lines370, trolley power is used to recharge the OBESS.

Position P 331 is the exit for the trolley ramp 371. The mining haultruck 302 is then uncoupled from the trolley lines 370. Powered by theOBESS, the mining haul truck 302 travels to position P 333 and then tothe unloading site 339, where the mining haul truck 302 unloads thepayload 304. The mining haul truck then departs the unloading site 339at position P 335 and moves to position P 337, the entrance to thetrolley ramp 361. The mining haul truck 302 is coupled to the trolleylines 360. Under trolley power, the mining haul truck 302 moves down thetrolley ramp 361 (shown as position P 363) and arrives at position P307. While the mining haul truck 302 is coupled to the trolley lines360, trolley power is used to recharge the OBESS.

Position 307 is the exit for the trolley ramp 361. The mining haul truck302 is then uncoupled from the trolley lines 360. Powered by the OBESS,the mining haul truck 302 moves to the position P 301 to start anotherwork cycle.

Refer to travel scenario shown in FIG. 4, which shows a mining site inwhich the loading site is uphill from the unloading site. The loadingsite 409 is located within the region 421. Within the region 421, themining haul truck 302 is not powered by trolley lines. The unloadingsite 439 is located within the region 451. Within the region 451, themining haul truck 302 is not powered by trolley lines. Typically, theterrain within the region 421 and within the region 451 is substantiallyflat.

In the uphill direction, the region 451 and the region 421 are connectedby the trolley ramp 471, along which trolley power is available from thetrolley lines 470. In the downhill direction, the region 421 and theregion 451 are connected by the trolley ramp 461, along which trolleypower is available from the trolley lines 460. The trolley lines 470 andthe trolley lines 460 are supported overhead by the support arms 412mounted on the support poles 410.

Powered by an OBESS, the mining haul truck 302 starts in region 421 atposition P 401 and moves to the loading site 409. At the loading site409, an electric shovel (not shown) fills the payload 404 (such as ore)onto the mining haul truck 302, which then leaves the loading site 409at position P 403. The mining haul truck 302 then moves to position P405, the entrance to the trolley ramp 461. The mining haul truck 302 iscoupled to the trolley lines 460. Under trolley power, the mining haultruck 302 moves down the trolley ramp 461 (shown as position P 463) andarrives at position P 431. While the mining haul truck 302 is coupled tothe trolley lines 460, trolley power is used to recharge the OBESS.

Position P 431 is the exit for the trolley ramp 461. The mining haultruck 302 is then uncoupled from the trolley lines 460. Powered by theOBESS, the mining haul truck 302 travels to position P 433 and then tothe unloading site 439, where the mining haul truck 302 unloads thepayload 404. The mining haul truck 302 then departs the unloading site439 at position P 435 and moves to position P 437, the entrance to thetrolley ramp 471. The mining haul truck 302 is coupled to the trolleylines 470. Under trolley power, the mining haul truck 302 moves up thetrolley ramp 471 (shown as position P 473) and arrives at position P407. While the mining haul truck 302 is coupled to the trolley lines470, trolley power is used to recharge the OBESS.

Position P 407 is the exit for the trolley ramp 471. The mining haultruck 302 is then uncoupled from the trolley lines 470. Powered by theOBESS, the mining haul truck 302 moves to the position P 401 to startanother work cycle.

A method for all electrical operation of a mining haul truck issummarized in the flowchart of FIG. 5A and FIG. 5B. In step 502, themining haul truck starts in region 1. In step 504, the on-board energystorage system (OBESS) is initially charged from an available electricalpower source (such as a charging station, trolley lines, or dieselengine and generator). In step 506, powered by the OBESS, the mininghaul truck travels within the region 1 (for example, travels to aloading site and receives a payload). In step 508, powered by the OBESS,the mining haul truck travels to the trolley ramp 1.

In step 510, the mining haul truck is coupled to the trolley lines 1. Instep 512, powered by the trolley lines 1, the mining haul truck departsregion 1. In step 514, powered by the trolley lines 1, the mining haultruck travels along the trolley ramp 1. The OBESS is charged byelectrical power from the trolley lines 1. In step 516, powered by thetrolley lines 1, the mining haul truck arrives at region 2.

In step 518, the mining haul truck is uncoupled from the trolley lines1. In step 520, powered by the OBESS, the mining haul truck travelswithin the region 2 (for example, travels to an unloading site and dumpsthe payload). In step 522, powered by the OBESS, the mining haul trucktravels to the trolley ramp 2.

In step 524, the mining haul truck is coupled to the trolley lines 2. Instep 526, powered by the trolley lines 2, the mining haul truck departsregion 2. In step 528, powered by the trolley lines 2, the mining haultruck travels along the trolley ramp 2. The OBESS is charged byelectrical power from the trolley lines 2. In step 530, powered by thetrolley lines 2, the mining haul truck arrives at region 1. In step 532,the mining haul truck is uncoupled from the trolley lines 2. The mininghaul truck has a charged OBESS and is ready to start another work cycle.

In an embodiment of the invention, the OBESS is charged with retardenergy from the wheel motors. To slow down a moving mining haul truck,the mining haul truck drive system operates in a retard mode. Undernormal operation, an electrical motor converts electrical energy intomechanical energy. The operating mode in which an electrical motorconverts electrical energy into mechanical energy is referred to as thepropel mode, and a time interval during which the electrical motoroperates in a propel mode is referred to as a propel interval. Anelectrical motor can also be operated in reverse as a generator toconvert mechanical energy into electrical energy (referred to as retardenergy), which is fed into inverters. The operating mode in which theelectrical motor converts mechanical energy into electrical energy isreferred to as the retard mode, and a time interval during which theelectrical motor operates in a retard mode is referred to as a retardinterval.

Typically, braking choppers, connected to the inverters, channel thepower into a power resistor grid that continuously dissipates the retardenergy until the mining haul truck reaches standstill; that is, theretard energy is dissipated as waste heat. Braking is smooth, similar tothe braking operation in a car, but without mechanical brake wear. Referto the prior-art power system shown in FIG. 2, for example. The chopper214 and the power resistor grid 216 provide the braking action for thewheel motor 212. Similarly, the chopper 222 and the power resistor grid224 provide the braking action for the wheel motor 220.

In an embodiment of the invention, however, an OBESS is integrated intothe mining haul truck power system to recover and store the retardenergy. In particular, when a mining haul truck is travelling downhill,substantial quantities of retard energy can be captured and stored(especially if the mining haul truck is carrying a heavy payload), sincethe mining haul truck is frequently braking, and therefore there arefrequent intervals during which the wheel motors are operating in theretard mode. Depending on the terrain, retard energy can also becaptured during the uphill trip; retard energy can also be capturedwhile the mining haul truck is travelling on level ground.

The retard energy is then used to charge the OBESS. In an embodiment ofthe invention, the OBESS is implemented with an ultracapacitor systemcomprising an ultracapacitor bank. The amount of energy that can bestored in the ultracapacitor system depends on the size of theultracapacitor bank. The OBESS can also be implemented with arechargeable battery system comprising a battery bank. The amount ofenergy that can be stored in the battery system depends on the size ofthe battery bank. The OBESS can also be implemented with combinations ofultracapacitor banks and battery banks. Storage capacity requirementsare described below.

An ultracapacitor can provide high power densities. For increasedelectrical energy storage, multiple ultracapacitors can be connected inseries and parallel to form an ultracapacitor bank. Electrical currentflowing into an ultracapacitor charges the ultracapacitor, andelectrical energy is stored via charge separation at anelectrode-electrolyte interface. The stored electrical energy can thenlater be used to output an electrical current. To maximize the lifetimeof an ultracapacitor, the ultracapacitor is not fully discharged.Typically, the ultracapacitor is discharged until its voltage drops to aminimum user-defined lower voltage limit. The lower voltage limit, forexample, can be one-half of the initial fully-charged voltage.

FIG. 6 shows a schematic of an OBESS 626 integrated into a trolley powersystem. The wheel motors 610 are powered by the motor drive system 630,which includes the DC link capacitor 606 and the inverters 608. Thetrolley DC power system 604 provides DC power to the motor drive system630 via trolley lines. In the example shown, the OBESS 626 includes theultracapacitor electrical energy storage unit 614 and the ultracapacitorenergy management controller 612. The ultracapacitor electrical energystorage unit 614 comprises the DC-to-DC converter 618, the choke/reactor622, and the ultracapacitor bank 624. The ultracapacitor electricalenergy storage unit 614 can be disconnected from the motor drive system630 via the connect/disconnect switch 616.

The ultracapacitor electrical energy storage unit 614 is managed by theultracapacitor energy management controller 612. The ultracapacitorenergy management controller 612 can also receive motor drive systemdata 628, which characterizes operation of the motor drive system 630.The motor drive system data 628 includes, for example, DC link voltage,current, and temperature. In response to control signals or controlcommands from the ultracapacitor energy management controller 612, theultracapacitor electrical energy storage unit 614 can (a) transmitelectrical energy to the wheel motors, (b) receive electrical energyfrom the trolley DC power system, or (c) receive retard electricalenergy from the wheel motors. If the ultracapacitor bank becomes fullycharged, excess retard energy can be dissipated in the grid resistors.Excess retard energy can also be transmitted via the trolley lines andstored in an auxiliary energy storage system or transmitted via thetrolley lines and returned to the utility grid via a bidirectionalelectric substation (as described in US Patent Application PublicationNo. 2011/0094841).

An embodiment of a computational system for implementing theultracapacitor energy management controller 612 (FIG. 6) is shown inFIG. 10. The computational system 1002 is typically located in themining haul truck; however, other locations are possible. One skilled inthe art can construct the computational system 1002 from variouscombinations of hardware, firmware, and software. One skilled in the artcan construct the computational system 1002 from various electroniccomponents, including one or more general purpose processors (such asmicroprocessors), one or more digital signal processors, one or moreapplication-specific integrated circuits (ASICs), and one or morefield-programmable gate arrays (FPGAs).

The computational system 1002 comprises the computer 1006, whichincludes a processor [referred to as the central processing unit (CPU)1008], memory 1010, and a data storage device 1012. The data storagedevice 1012 comprises at least one persistent, tangible computerreadable medium, such as non-volatile semiconductor memory, a magnetichard drive, and a compact disc read only memory. In an embodiment of theinvention, the computer 1006 is implemented as an integrated device.

The computational system 1002 can further comprise a user input/outputinterface 1014, which interfaces the computer 1006 to a userinput/output device 1022. Examples of the input/output device 1022include a keyboard, a mouse, and a local access terminal. Data,including computer executable code, can be transferred to and from thecomputer 1006 via the input/output interface 1014.

The computational system 1002 can further comprise a communicationsnetwork interface 1016, which interfaces the computer 1006 with a remoteaccess network 1024. Examples of the remote access network 1024 includea local area network and a wide area network (communications links canbe wireless). A user can access the computer 1006 via a remote accessterminal (not shown). Data, including computer executable code, can betransferred to and from the computer 1006 via the communications networkinterface 1016.

The computational system 1002 can further comprise the ultracapacitorelectrical energy storage unit interface 1018, which interfaces thecomputer 1006 with the ultracapacitor electrical energy storage unit 614(see FIG. 6). The computational system 1002 can further comprise a motordrive system interface 1020, which interfaces the computer 1006 with themotor drive system 630 (see FIG. 6). The motor drive system interface1020, for example, receives the motor drive system data 628.

As is well known, a computer operates under control of computersoftware, which defines the overall operation of the computer andapplications. The CPU 1008 controls the overall operation of thecomputer and applications by executing computer program instructionsthat define the overall operation and applications. The computer programinstructions can be stored in the data storage device 1012 and loadedinto memory 1010 when execution of the program instructions is desired.

The method steps shown in the flowchart in FIG. 5A and FIG. 5B can bedefined by computer program instructions stored in the memory 1010 or inthe data storage device 1012 (or in a combination of memory 1010 and thedata storage device 1012) and controlled by the CPU 1008 executing thecomputer program instructions. For example, the computer programinstructions can be implemented as computer executable code programmedby one skilled in the art to perform algorithms implementing the methodsteps shown in the flowchart in FIG. 5A and FIG. 5B. Accordingly, byexecuting the computer program instructions, the CPU 1008 executesalgorithms implementing the method steps shown in the flowchart in FIG.5A and FIG. 5B.

Required storage capacity of the OBESS can be estimated fromcalculations. For example, assume the following haul profile (travelscenario similar to that shown in FIG. 3):

-   -   500 m, flat: shovel (loading site) to trolley ramp, loaded    -   2000 m, 10% grade: trolley ramp, loaded    -   500 m, flat: trolley ramp to dump (unloading site), loaded    -   500 m, flat: dump to trolley ramp, empty    -   2000 m, −10% grade: trolley ramp, empty    -   500 m, flat: trolley ramp to shovel, empty.        Each leg of the profile specifies (a) the distance traveled, (b)        slope of ground, (c) travel path, and (d) payload status of the        mining haul truck. The weight of the empty mining haul truck is        assumed to be 160,000 kg; and the weight of the loaded mining        haul truck is assumed to be 400,000 kg.

The speed and acceleration for the mining haul truck running on theabove profile is shown in FIG. 7. Plot 702 shows the vehicle speed(km/hr) as a function of travel time (s). Plot 704 shows the vehicleacceleration (m/s²) as a function of travel time (s). Refer to FIG. 8.Plot 802 shows the vehicle tractive effort (kN) as a function of traveltime (s). Plot 804 shows the vehicle drive drag (kN) as a function oftravel time (s). Refer to FIG. 9. Plot 902 shows the travel distance (m)as a function of travel time (s).

From FIG. 7, it can be seen that the mining haul truck needs about 50 sto reach the trolley ramp. Similarly, it would require about the sametime to travel from the trolley ramp to the dump (unloading site).Returning from the dump to the trolley ramp would require less timesince the mining haul truck is empty. The mining haul truck needsapproximately 24 kWh of energy from the OBESS to move the mining haultruck from the shovel (loading site) to the trolley ramp. For all otherareas, the energy required from the OBESS would be equal to or less than24 kWh.

Selection of the appropriate energy storage device is important. Minesare often located in remote locations with extreme climatic conditions.Extreme cold conditions with temperatures below −20° C. pose particularchallenges. In addition, mining haul trucks are subjected to extremeshocks and vibrations. Appropriate candidates for energy storage aretraction grade ultracapacitors and traction grade batteries.

Refer back to the travel scenarios shown in FIG. 3 and in FIG. 4.Trolley power is supplied on both the uphill path and the downhill path.In some scenarios, trolley power is not needed on the downhill path ifthe OBESS is sufficiently charged at the start of the downhill path, andif sufficient retard energy is generated along the downhill path tomaintain sufficient charge in the OBESS for the mining haul truck tooperate, while powered by the OBESS, along the entirety of the downhillpath and within the downhill region (region 321 in FIG. 3 or region 451in FIG. 4).

Embodiments of the invention can be retrofitted into an existing mininghaul truck that has a diesel engine and a generator. The diesel enginecan be retained for operation under fault conditions or used to chargethe OBESS while idling. In other embodiments of the invention, a mininghaul truck is not equipped with a diesel engine and generator: themining haul truck is propelled by electrical power supplied by trolleylines alone, an OBESS alone, or a combination of trolley lines and anOBESS.

Embodiments of the invention have been described with reference to amining haul truck. One skilled in the art can develop embodiments of theinvention for other vehicles driven by electrical motors.

The foregoing Detailed Description is to be understood as being in everyrespect illustrative and exemplary, but not restrictive, and the scopeof the invention disclosed herein is not to be determined from theDetailed Description, but rather from the claims as interpretedaccording to the full breadth permitted by the patent laws. It is to beunderstood that the embodiments shown and described herein are onlyillustrative of the principles of the present invention and that variousmodifications may be implemented by those skilled in the art withoutdeparting from the scope and spirit of the invention. Those skilled inthe art could implement various other feature combinations withoutdeparting from the scope and spirit of the invention.

1. A method for supplying electrical power to an electrical motor on anall electrically powered mining haul truck, the method comprising thesteps of: charging an on-board energy storage system with electricalpower from a trolley power system while the mining haul truck is coupledto trolley lines of the trolley power system; uncoupling the mining haultruck from the trolley lines; and supplying electrical power to theelectrical motor from the on-board energy storage system while themining haul truck is uncoupled from the trolley lines, wherein themining haul truck is propelled by electrical power supplied by thetrolley power system alone, or by the on-board energy storage systemalone, or a combination of the trolley power system and the on-boardenergy storage system, without mechanical power supplied by a mechanicalengine to propel the mining haul truck.
 2. The method of claim 1,wherein: the on-board energy storage system comprises at least oneultracapacitor.
 3. The method of claim 1, wherein: the on-board energystorage system comprises at least one battery.
 4. The method of claim 1,further comprising: supplying electrical power to the electrical motorfrom the trolley power system while the mining haul truck is travellingon an uphill grade; and charging the on-board energy storage system withelectrical power from the trolley power system while the mining haultruck is travelling on the uphill grade.
 5. The method of claim 1,further comprising: supplying electrical power to the electrical motorfrom the trolley power system while the mining haul truck is travellingon a downhill grade; and charging the on-board energy storage systemwith electrical power from the trolley power system while the mininghaul truck is travelling on the downhill grade.
 6. The method of claim1, further comprising: charging the on-board energy storage system withelectrical power generated by the electrical motor during braking of themining haul truck.
 7. The method of claim 4, further comprising:charging the on-board energy storage system with electrical powergenerated by the electrical motor during braking of the mining haultruck.
 8. The method of claim 5, further comprising: charging theon-board energy storage system with electrical power generated by theelectrical motor during braking of the mining haul truck.
 9. Anelectrical power system for supplying electrical power to an electricalmotor on an all electrically powered mining haul truck, the electricalpower system comprising: an on-board energy storage system; an inverterconfigured to: receive electrical power from the on-board electricalenergy storage system; receive electrical power from a trolley powersystem; and supply electrical power to the electrical motor; and acontroller configured to: charge the on-board energy storage system withelectrical power from the trolley power system while the mining haultruck is coupled to trolley lines of the trolley power system; andsupply electrical power to the electrical motor from the on-board energystorage system, wherein the mining haul truck is configured to bepropelled by electrical power supplied by at least one of the trolleypower system alone, the on-board energy storage system alone, or acombination thereof without mechanical power supplied by a mechanicalengine to propel the mining haul truck.
 10. The electrical power systemof claim 9, wherein: the on-board energy storage system comprises atleast one ultracapacitor.
 11. The electrical power system of claim 9,wherein: the on-board energy storage system comprises at least onebattery.
 12. The electrical power system of claim 9, wherein: theon-board energy storage system is configured to be charged withelectrical power generated by the electrical motor during braking of themining haul truck.
 13. The electrical power system of claim 9, whereinthe controller is further configured to: supply electrical power to theelectrical motor from the trolley power system while the on-board energystorage system is being charged by the trolley power system.
 14. Amethod for operating an all electrically powered mining haul truckcomprising an electrical motor, the method comprising: charging anon-board energy storage system with electrical power from a trolleypower system while the mining haul truck is coupled to trolley lines ofthe trolley power system; uncoupling the mining haul truck from thetrolley lines; supplying electrical power to the electrical motor fromthe on-board energy storage system; driving the mining haul truck to aloading site; and filling the mining haul truck with a payload, whereinthe mining haul truck is propelled by electrical power supplied by thetrolley power system alone, or by the on-board energy storage systemalone, or a combination of the trolley power system and the on-boardenergy storage system, without mechanical power supplied by a mechanicalengine to propel the mining haul truck.
 15. The method of claim 14,further comprising: charging the on-board energy storage system withelectrical power generated by the electrical motor during braking of themining haul truck.
 16. The method of claim 14, further comprising:driving the mining haul truck to a trolley ramp; coupling the mininghaul truck to the trolley lines; supplying electrical power to theelectrical motor from the trolley lines; driving the mining haul truckalong the trolley ramp; and charging the on-board energy storage systemwith electrical power supplied from the trolley lines.
 17. The method ofclaim 16, further comprising: charging the on-board energy storagesystem with electrical power generated by the electrical motor duringbraking of the mining haul truck.
 18. The method of claim 16, furthercomprising: driving the mining haul truck to an unloading site; andunloading the payload from the mining haul truck.
 19. The method ofclaim 18, further comprising: charging the on-board energy storagesystem with electrical power generated by the electrical motor duringbraking of the mining haul truck.
 20. The method of claim 14, wherein:the on-board energy storage system comprises at least one ultracapacitoror at least one battery.